Publications

We have recently developed a new theoretical approach to the study of polymer liquids. The theory is based on the reference interaction site model'' (RISM theory) of Chandler and Andersen, which has been successful in describing the structure of small molecule liquids. We have recently extended our polymer RISM theory to the case of polymer blends. In the present investigation we have applied this theory to two special binary blends: (1) the athermal mixture where we isolate structural effects, and (2) the isotopic mixture in which structurally identical polymer chains interact with dissimilar attractive interactions. By studying these two special cases we are able to obtain insights into the molecular factors which control the miscibility in polymer mixtures. 18 refs., 2 figs.

A refrigerated Dewar has been used successfully with the Josephson array voltage calibration system. It has been used to re-liquefy helium with no degradation of the calibration system's performance. The independence of the array voltage from temperature has been confirmed to three parts in 10{sup 8} per Kelvin using this Dewar. 6 refs., 3 figs.

In summary, through thermal/structural calculations and detailed comparisons of the results of a large scale, in situ heated experiment at the WIPP facility, it should be possible to validate the temperature dependence of room deformation. The experiment, when used in conjunction with an identical experimental room which was unheated, is very specific to only the thermal portions of the calculational model. 4 refs., 6 figs.

A nuclear waste management system presents a challenge to organize a development program that can effectively achieve the goal of providing timely solutions to the problem of nuclear waste management. A few distinguishing factors can serve to aid the establishment of an effective program.

A new technique for tunnel detection and location has recently been theoretically modeled and experimentally demonstrated. The objective of this research is to develop a general method for remotely detecting the presence of unauthorized tunneling activities using one or more boreholes and a surface source. A line current or dipole-dipole array, positioned on or near the surface of the earth, is used as the TE current source. Subsurface electric and magnetic field measurements are made in a borehole that is situated near a suspected tunnel location. The presence of a tunnel causes subsurface scattering of the field components created by the source. Both the electric and magnetic field strength and phase data is perturbed by the presence of a nearby tunnel. The scattered fields are observed on both sides of the tunnel relative to the source position. 1 fig.

This talk was given at the 14th International Pyrotechnic Seminar on September 21, 1989, in Jersey, United Kingdom, as one of two plenary lectures. It briefly surveys the current technology of pyrotechnic devices and examines trends for the future. The pyrotechnic'' can have several meanings. In this talk, pyrotechnic devices'' are devices in which porous materials undergo reduction-oxidation reactions and produce useful products. The pyrotechnic materials are generally fuel-oxidizer systems without binders, in contrast to primary or secondary explosives or propellants. The word pyrotechnic'' is often used to include explosive, squib, propellant, or other ordnance type devices, especially in the European community. The major need for pyrotechnic devices has always been military and defense; however, as technology advances, the civilian uses of pyrotechnics will continue to grow. If every automobile had a pyrotechnic device to trigger its air or crash bag, that application alone would mean millions of devices per year. Applications in safety, fire fighting, law enforcement, and other commercial applications are likely to increase due to the increased capability of pyrotechnic devices and the integration of such devices in system designs. 2 refs., 56 figs.

Computed torque algorithms are used to compensate for the changing dynamics of robot manipulators in order to ensure that a constant level of damping is maintained for all configurations. Unfortunately, there are three significant problems with existing computed torque algorithms. First, they are nonpassive and can lead to unstable behavior; second, they make inefficient use of actuator capability; and third, they cannot be used to maintain a constant end-effector stiffness for force control tasks. Recently, we introduced a new control algorithm for robots which, like computed torque, uses a model of the manipulator's dynamics to maintain a constant level of damping in the system, but does so passively. This new class of passive control algorithms has guaranteed stability properties, utilizes actuators more effectively, and can also be used to maintain constant end-effector stiffness. In this paper, this approach is described in detail, implementation issues are discussed, and simulation results are given. 15 refs., 6 figs., 2 tabs.

We have performed nanosecond-resolution measurements of the lateral electrical resistivity of thin metal films on insulating substrates. Comparison of transient resistivity measurements with optical reflectivity measurements and heat-flow calculations permits the determination of the position and velocity of a planar crystal/melt in interface, and an estimate of undercooling during pulsed laser melting of metals. We report detailed results for rapid solidification of Ni, including the observation of hypercooling of liquid Ni. 14 refs., 3 figs., 1 tab.

Spent pressurized-water reactor (PWR) and boiling-water reactor (BWR) fuel rods from three reactors were examined by hot cell periscope, energy dispersive x-ray analysis, and scanning electron micrography. In the case of fuel from the Quad Cities reactor, it was possible to develop a complete particle size distribution. It was found to be log-normal, with a median geometric diameter of 3 {mu}m and a standard deviation of 1.87 {mu}m. 5 refs., 5 figs., 1 tab.

Sandia National Laboratories (SNL) performs software security analyses of many systems having strong security requirements. This paper gives an overview of a software security analysis methodology that has evolved at SNL. This methodology is based on experience gained in the analysis of critical software-controlled systems. The paper describes analysis activities and how they relate to the traditional software life cycle. Topics discussed include: planning for the analysis; supporting the development and documentation of security requirements; identifying and analyzing the threat; acquiring and utilizing software design and implementation materials; identifying positive design features; scaling the analysis effort to the threat; analyzing the high-level design; analyzing the source-code and target implementations; reporting results; interacting with system and component development groups; and supporting the authentication of the software product before it is fielded. The paper also stresses the importance of independence of analysis and development groups.

E-beam excitation of the atomic xenon laser is theoretically and experimentally investigated using short-pulse high-power deposition (>MW/cm{sup 3}-atm) and low-power high-energy loading ({le}1 kJ/{ell}-atm). Scaling laws are derived to maximize laser power and energy efficiency. 4 refs.

An adaptive, swing-free trajetory planner for a gantry robot has been analytically developed and experimentally implemented on a commercial robot. A batch, nonlinear least square estimator (differential correction) is used to predict the initial conditions, mass, and frequency of the simply suspended object from a set of force sensor measurements. These parameters, in turn, are supplied to the swing-free trajectory planner to perform the maneuver. These algorithms have been implemented on a CIMCORP XR6100 gantry robot, and swing-free trajectories have been performed by the robot using the adaptive trajectory planner.

Angularly accelerating a cantilevered rod which sags under gravity couples the out-of-plane dynamics of the flexible rod and causes oscillation in both the horizontal and vertical planes. A parameter-scheduled trajectory planner has been analytically developed and experimentally implemented on a commercial robot to suppress the first mode of these vibrations during a horizontal angular move. A load was attached to the tip of the rod and the resulting static, out-of-plane, hub torque was measured with a force-torque sensor. This torque was used to predict the period of the horizontal first mode of vibration of the payload (rod and attached load) from a nonlinear function in order to calculate (schedule) the appropriate control parameters for the angular move. This system has been implemented on a Cincinnati Milacron T3-786 robot, and vibration suppressed trajectories (which reduce the coupled residual vibrations by over 90%) have been performed by the robot for various payloads. 9 refs., 3 figs., 2 tabs.

Accurate motion control of wheeled mobile robots (WMRs) is required for their application to autonomous, semi-autonomous and teleoperated tasks. The similarities between WMRs and stationary manipulators suggest that current, successful, model-based manipulator control algorithms may be applied to WMRs. Special characteristics of WMRs including higher-pairs, closed-chains, friction and unactuated and unsensed joints require innovative modeling methodologies. The WMR modeling challenge has been recently overcome, thus enabling the application of manipulator control algorithms to WMRs. This realization lays the foundation for significant technology transfer from manipulator control to WMR control. We apply two Cartesian-space manipulator control algorithms: resolved motion rate (kinematics-based) and resolved acceleration (dynamics-based) control to WMR servo-control. We evaluate simulation studies of two exemplary WMRs: Uranus (a three degree-of-freedom WMR constructed at Carnegie Mellon University), and Bicsun-Bicas (a two degree-of-freedom WMR being constructed at Sandia National Laboratories) under the control of these algorithms. Although resolved motion rate servo-control is adequate for the control of Uranus, resolved acceleration servo-control is required for the control of the mechanically simpler Bicsun-Bicas because it exhibits more dynamic coupling and nonlinearities. Successful accurate motion control of these WMRs in simulation is driving current experimental research studies. 18 refs., 7 figs., 5 tabs.

Detailed models and analytical procedures are applied to the many complex aspects of spent fuel in transport including characterization of the fuel's irradiation conditions and initial states at the time of shipment, determination of the dynamic forces on the fuel assemblies that result from regulatory transportation accidents, modeling and analysis of the fuel's mechanical response to these forces, and estimation of the releasable radioactivity in the event of cladding breach. The methodology adopts a combined deterministic/probabilistic analysis approach in which each aspect of the problem is appropriately treated on the basis of its level of determinability. The results are obtained in the form of failure probabilities for each regulatory event considered. 3 refs., 6 figs.

An accepted technique for simulating pyrotechnic shock inputs has been the resonant plate test. The plate is designed so that its predominant modes generate the desired frequency content of a given shock test specification. The success of the test is dependent on the engineer's ability to effectively design and control the response of the resonant plate. In designing a test to simulated a pyrotechnic environment, the location and mass of the test item become very important considerations since they have a profound impact on the dynamic response of the resonant plate. A relatively massive test item can change the plates's resonant frequency. Differences in the relative frequencies of the test item's fixture and the resonant plate may also effect the input to the test items. In this study, a simple mock test assembly is used to study test item and resonant plate interactions during a test. The implications of this interaction regarding the deviations of the shock test specification are also discussed. Data from shock tests performed with the test assembly mounted to a rigid mounting surface and a flexible resonant plate are compared. Frequency response functions and shock response spectra are generated from the test data and compared to show the significance of: (1) the relative stiffness of the mounting surface; and (2) the location of the input control point during a resonant plate test. These factors are shown to be particularly important in using resonant plate testing to simulate pyrotechnic shock environments. 5 refs., 7 figs.

In the early 1980s, the US Department of Energy/Defense Programs (DOE/DP) initiated a project to develop a safe and efficient transportation system for defense high-level waste (DHLW). Sandia National Laboratories (SNL) provides a technical oversight and test support and General Atomics provides the design and safety analysis of the shipping system. The specific activities include designing, testing, certifying and fabricating a legal-weight truck cask system for DHLW canisters that are expected to be first produced by the Defense Waste Processing Facility (DWPF) at the Savannah River Plant (SRP) in South Carolina and later produced by facilities in Washington and Idaho. A truck cask was selected in order to provide a flexible capability for transporting vitrified waste to support a variety of expected experimental program needs. The first planned shipping campaign was to transport a limited number of DHLW canisters from South Carolina to the Waste Isolation Pilot Plant (WIPP) in New Mexico. However, changes in experimental program plans the passage of the Nuclear Waste Policy Act in late 1982, and the subsequent decision to have DHLW permanently placed in the eventual civilian repository resulted in revisions to the mission of the cask development program funded by DOE/DP. 15 refs.

This reference consists of a video cassette demonstration of the Fire Ant. This video is 5 minutes in duration and effectively demonstrates the usefulness of the remote controlled Fire Ant.

The GTA weldability and fracture behavior of low and high carbon arc cast and powder metallurgy molybdenum has been examined. Defect-free welds were produced in the arc cast grades. For the PM grade, however, severe centerline cracking and large scale porosity were encountered. The center-line cracking and pore formation were found to result from the dissolution of oxygen-bearing inclusions present in the starting material. Moreover, titanium or hafnium additions, incorporated into the weld by RF sputter coating the joints prior to welding, had several beneficial effects. These were reductions in the centerline cracking and pore formation in the PM welds, hardening of the weld fusion zone, and a reduction in the tendency for intergranular failure in the fusion zone for all base materials. The mechanisms by which dopant additions improve the welding and fracture behavior is also discussed. 22 refs., 16 figs., 2 tabs.

TORE SUPRA is a fairly large tokamak and has an original goal to withstand a large power removal (25 MW) during a 30 seconds long pulse. One of the main energy removal system's is the inner first wall which was originally designed for the following aims: protect the inner side of the vacuum vessel from normal plasma operation (participates to the plasma power removal) and against disruptive events (plasma energy quench and current decay); act as a toroidal belt limiter during steady state operation and plasma start up; and protect the vacuum vessel from the shine through of the neutral beam injectors and act as a beam dump for short shots. In order to match those different goals the design choice was oriented towards an actively cooled graphite wall capable to sustain an 1 MW/m/sup 2/ continuous heat flux. This paper discusses this design concept further.

Measurements of arc and melting efficiencies have been made for pulsed and continuous mode Gas Tungsten Arc Welding (GTAW) and Plasma Arc Welding (PAW) processes. Welds were made on 2.5 mm total thickness pure Ni and 304 Stainless Steel in a standing edge weld geometry at constant nominal machine output settings which varied average current with travel speed. Under continuous current conditions, the measured heat input remained approximately constant for the conditions examined (250-1250 mm/min), while melting efficiency increased dramatically (0-/approximately/0.4). Arc efficiencies were relatively constant, remaining in the range of /approximately/0.75-0.85 for GTAW and somewhat less for PAW. Values of melting efficiency for Ni were slightly less than those for 304 when compared at similar travel speeds, though both tended toward the same limit (/approximately/0.4). The PAW results were not appreciably higher than the GTAW. In addition to melting efficiency the centerline depth of penetration was also measured. In contrast to the GTAW results, which increased with speed at lower travel speeds and then plateaued at 0.8 mm, the PAW results increased monotonically with speed to a maximum of 1.0 mm. In conclusion, calorimetric measurements of nonconsumable arc welding processes have been found helpful in understanding conditions under which efficient arc welds with minimal heat inputs for a desired weld penetration can be made. 10 figs.

The clean rooms in the new Radiation Hardened Integrated Circuit (RHIC-II) Facility have become operational. Design philosophy and information on the air handling system, initial data on particulate contamination levels in clean bays, service chases and the make up air system will be presented. Data on power consumption, particulate levels before and after the HEPA filters and sound levels with air velocities from 95 to 57 feet per minute will be reported. 2 refs., 5 figs., 4 tabs.

In experimental fusion energy devices such as tokamaks, pump limiters are used to define the plasma edge as well as control the plasma density and impurity. Since these devices must operate at the edge of the plasma, they are subject to high heat flux incidence from the plasma side. In this paper, one of the active heat removal schemes considered for the outboard pump limiter of Tore Supra, a tokamak under construction in Cadarache, France, is analyzed in some detail. The scheme involves cooling by forced convective nucleate boiling of water at the limiter leading edges and by forced convection of high pressure helium at its front face. 14 refs., 5 figs., 4 tabs.

This report discusses the projects and device support for the following thermonuclear reactors: Tokamak Fusion Test Reactor, Compact Ignition Tokamak, International Thermonuclear Experimental Reactor, Joint European Torus, Textor, Tore-Supra, DIII-D, and ASDEX and ASDEX Upgrade. This paper also discusses High-Heat Flux Materials and Components and Plasma Surface Interactions Research.

This report is a table listing spare parts for the B83-0 type 3C. An explanation for information in each column is given. This issue supersedes Issue F, dated March 22, 1985.